Weapon porgression bonuses are not disabled in Classic or in Custom when using "No Progression Bonuses" setting. The only way we have found to disable the weapon progression bonuses is setting the "Maximum Weapon Proficiency Level" setting on 1, but this has side-effects: it makes the server custom and unranked, and when using Realism load-out, it also limits the weapon unlocks to level 1.
How we discovered this: in a Classic server, spawn with a weapon which you leveled to level 50. Time how long it takes to reload this weapon. Next, go to a custom server with the "Maximum Weapon Proficiency Level" setting on 1, and do the same reload. You will notice the reload is about 20% slower.
How we discovered this: in a Classic server, spawn with a weapon which you leveled to level 50. Time how long it takes to reload this weapon. Next, go to a custom server with the "Maximum Weapon Proficiency Level" setting on 1, and do the same reload. You will notice the reload is about 20% slower.